Math Dad
January 15th, 2009

Math Dad

EDIT:
Given the amount of attention the math on this comic has received, if you really want a version with math that works out a little better… ask and ye shall receive.

^ 55 Comments...

  1. Scott Simonsen

    great first frame set up, great colors, great four panel storytelling

  2. Charlie Croom

    Agree with the above comment, and I like the very small detail on the 4th question of “where does he keep his gun?” :-P

  3. domesauce

    holy crap i didn’t even notice that gun part

  4. James

    This is also very funny. I also like the hidden gun. How long do each of these take to make, also put them in a magazine or noteboook and I’ll buy one.

  5. nate

    Wait, If the second comment means that his dad in 5 years time is 3 times the kids age plus 6. Then that makes the kid 22!
    Of if his age is 3x(the kids + 6) the kids still 17.

    ahem….

  6. Eric

    Hmm, it seems then that the father is 79 and the son is 22…

  7. Warren

    I’m glad to see I wasn’t the only one who felt compelled to solve it!

  8. Juice

    Okay, so what we have is the following:
    (x+5-1)4=y and (x+6)3=y
    Simplified, we come to:
    x^4=(x^3)+2

    From there, I can’t figure it out. However, I do know the kid is not 22 or 17 as suggested above. Any bigger math geeks than me?

  9. Cole

    WHOA there buddy I have no idea how you brought powers into this.
    it should really be:
    4(x-1)=y+5 and 3(x+6)=y+5
    4x-4=3x+18
    x=22
    y+5=4(21)=84
    y=79

    The masses are right. We really just chose numbers that looked good, since the fact that the kid would know his own age makes it ridiculous for his dad to give him two equations anyways. But nonetheless it was a foolish and lazy choice.

    Although consider this: maybe he’s just a really bad math teacher

  10. Blaine

    The first answers are right, it’s 22 and 79.
    The equations to set it up are x+5=4(y-1) and x+5=3(y+6). x is the dad, y is the kid.
    I knew algebra would come to use somehow in life outside school.

  11. Matt

    In the one where the maths works better, the kid is 5 and the father is 25.

    5x = 4x+5

  12. pmwflm

    You obviously don’t understand the equation matt. You are leaving out the second part. (5+1)*3 is not 25+1.

  13. Scott

    Actually, I think the kid is 8 and the dad is 37, but I was never any good at algebra.

  14. charles

    ha ha ya I hate when people make stuff harder then it needs to be. But I think the kids 4?

  15. Peter

    He’s 6.

  16. Steveb

    There is no possible way to solve this, you need to know the age of the father or the child

  17. Colin

    steveb, how hard did you fail algebra in school?

  18. jeff

    Steveb, you may think its impossible to solve now…but 7th grade math will blow your mind! ;)

  19. Bill

    3+4(x+2)=y
    5x+y

    solve x in terms of y to get x=Y/5
    Pluge in x in terms of y into the second equation to get 3+4((Y/5)+2)=Y
    then solve for them both to get
    Dad is 55
    and the Son is 11

  20. Brent

    eq1: 4(x+2) = y + 3 and eq2: 5x = y+3
    eq1: 4x + 8 = y +3
    eq1: 4x + 5 = y
    eq2: 5x = (4x + 5) + 3
    eq2: 5x = 4x + 8
    eq2: x = 8

    x[son] = 8
    y[dad] = 37

  21. Paul

    Great strip – perfect timing – keep up the good work.
    http://www.SamTheDecider.com

  22. dmgi

    For the first:

    4(x-1)=y+5 & 3(x+6)=y

    Assuming y represents the father’s age,

    4x-9=3x+18

    4x=3x+27

    x=27, being the kid’s age

    y=99

    Now, for the revised one,

    y+3=4(x+2) & 5x=y

    5x+3=4x+8

    5x=4x+5

    x=5

    y=25

    Pretty sure it’s correct, feel free to correct me, though

  23. Phil

    When you get your answers for both the son and the father, look back at the comic. Add 5 to the father’s age and subtract 1 from the son’s age. Now ask yourself if the father is four times as old. The only answer that works is 79 and 22.

    In five years (79+5 = 84) the father will be 4 times as old as the son was last year (22-1 = 21).

    Please check your work before you post thinking that you’re correct.

  24. Dionysus

    @dmgi

    4 * -1 != -9

    :)

  25. mathie

    k=kid’s age; d=dad’s age;

    (k-1)*4=d+5; (in 5 years, I will be 4x as old as you were last year)
    (k+6)*3=d; (and 3 times as old as you will be in 6 years);

    Strategy: Solve both for d, and set them equal, solve for k:
    ————————————————————————–
    eq.1: Distribute
    4k-4=d+5
    subtract 5 from both sides
    4k-9=d

    eq.2: distribute
    (k+6)*3=d
    3k+18=d

    Set 3k+18=4k-9 (both expressions equal d, therefore they are equal to each other)

    subtract 3k from both sides, add 9 to both sides:

    27=k

    kid’s age is 27!

    use kids age to solve for dad’s age:

    (27+6)*3=d
    33*3=d
    99=d

    Dad is 99!
    Kid is 27!

  26. Mike D

    How is everyone getting this wrong / bringing powers into this / saying it cannot be solved??

    according to some paint.exe algebra, it’s 22 & 79

  27. dmgi

    Dionayus,

    I substracted the five on the other side, sorry my work wasn’t that clear, but doing math notatuon on the iPhone is a pain in the ass with variables.

  28. dmgi

    Sorry for misspelling your name.

  29. rodneymcname44

    Haha, very impressive. I love the artwork, coloring and definitely the punch-line. I wasn’t expecting much, but was quite impressed!

  30. CowPi

    Much confusion is caused by assumptions made in the second bubble in panel 3.

    There are at least three “possible” ways to interpret the situation.

    One way is according to dmgi and mathie. This models traditional algebra word problems involving age. (Since there are two unknowns, it takes two equations to solve.)

    in five years DAD will be four times as old as SON was last year ==> dad + 5 = 4 * (son – 1)

    DAD IS three times as old as SON will be in six years ==> dad = 3 * (son + 6)

    They both correctly solved this problem to find son = 27 and dad = 99.

    Another way is purposed by Phil and Mike D. They do not not show their “work” like good math students, but this method finds their answers.

    in five years DAD will be four times as old as SON was last year ==> dad + 5 = 4 * (son – 1)

    in five years DAD will be three times as old as SON will be in six years ==> dad + 5 = 3 * (son + 6)

    This finds the son = 22 and dad = 79.

    There is a third way to see it:

    in five years DAD will be four times as old as SON was last year *AND* three times as old as SON will be in six years ==> dad + 5 = 4 * (son – 1) + 3 * (son + 6)

    Unfortunately, this does not directly solve the problem, BUT it does generate a formula for the son to calculate his dad’s age based on the son knowing his own age ==> dad = 7 * son + 9

  31. CactusRat

    I’m sorry, but you’ve all failed miserably at math, so I’ll break this down…

    Since the Dad gives two equations for his age, and his age has to be the same, we can set the two equations equal to each other.

    E1: In five years I will be four times as old as you were last year…
    Childs age = x

    4(x-1) + 5

    E2: Three times as old as you will be in six years.

    3(x+6)

    **Algebra time**

    4(x-1) + 5 = 3(x+6)

  32. MeTaL Cp

    jesus christ… i’ve never seen a bigger comment fail in my life
    whoever didn’t get the son being 22 in the original comic and him being 8 in the new one
    go get your gun
    and let natural selection take over
    original:
    x= kid’s age
    y=dad’s age

    equation 1
    4(x-1)=y+5
    4x-4=y+5

    equation 2
    3(x+6)=y+5
    3x+18=y+5

    3x+18=4x-4
    x=22
    y=4(22-1)-5
    y=84-5
    y=79

    everyone follow so far???

    new comic
    same variables

    equation 1
    4(x+2)=y+3
    4x+8=y+3

    equation 2
    5x=y+3

    4x+8=5x
    x=8

    y=5x-3
    y=37

    CactusRat… if your gonna call people out… at least get it right
    your equation comes out with 19… that is wrong… do not think otherwise

    but i wasn’t kidding get your gun and shoot yourself.
    i know shooting yourself seems difficult, and yes it’s hard
    make sure the safety is off
    make sure the gun is loaded
    point it at either your head or put the barrel in your mouth if you have bad aim
    squeeze the trigger… so many people say pull
    that’s incorrect… it’s squeeze

  33. MikeM

    Um, not for anything, but CactusRat’s equation equals 17, NOT 19.

    4(x-1)+5=3(x+6)
    4x-4+5=3x+18
    4x+1=3x+18
    4x=3x+17
    x=17

    That said, you are correct that the ages are 22/79.

    I’ve never seen this much hostility over math before…..

  34. MeTaL Cp

    haha… my bad about messing up CactusRats dumb equation… i messed it up out of anger… why are people so dumbI(i guess including me)?

  35. Tytyvyllus

    Just for fun, can we throw in Pi, log and maybe some i as well? It’s a great comic, the correct answer to the math problem is not important. For argument’s sake though, the father may have not actually thought out the question and was just trying to confuse the son anyways.
    But if you really want to squabble about it, be my guest.
    /facepalm

  36. i rule at math

    4x/5^2
    x/(3.14)/log(x)/3
    2^(x/3.14)-4x/5^2

    the kid is clearly 22

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  39. J

    I have never read more hilarious comments on a webcomic. Ever.
    Win.

  40. jm

    were talking about 1 age here (the kids age). with that, you get what the age of the dad is by plugging in the kids age into the formula. i dont know why you guys had to put in 2 variables.

    heres what i got.

    4(x-1)+5 = 3x + 6
    4x -4 +5 = 3x + 6
    4x +1 = 3x + 6
    x = 5

    plugging in the variable.

    4 ( 5 -1 ) + 5 = 21
    and
    3(5) + 6 = 21.

  41. Cat

    Jm, this is a two variable equation because you have to find x and y, you just skipped the first step/did it in your head (making both equations equal to y so you can drop a variable), but either way yours is wrong because you are saying 3x+6 when it should be 3(x+6) +5

    In most of the equations with the wrong answers people are only putting + 5 in the first equation when it needs to be in both.
    4x-4=y+5
    3x+18=y+5

    but it’s kind of confusing because if they’d bothered to check their answers they would have seen that they were wrong. I mean didn’t every high school math teacher ever tell you to go back and check all your answers?

    and for the record… this is MATH! There are not “several” correct answers. There are not “ways to look at it” there may be different ways to solve or write an equation but if you aren’t getting the same answer then your equation is wrong or solved incorrectly.

  42. Rondo

    I second J above. Hilarious.

  43. MenaceMind

    Best.Comic.Comments. EVER!

  44. OrthodoxAtheist

    H’okay… ages are 8 and 37 respectively in corrected version (http://www.qgmindpolice.com/wp-content/uploads/2009/03/2009-01-15-mathdad2.png). The world is at peace again finally. Poor cartoonist, haunted evermore due to the internet’s ability to link to superseded material. lolz

    (corrected version math for lazy people:
    kid’s age is x
    dad’s age is y

    y + 3 = 4(x + 2)
    y + 3 = 5x
    5x = 4x + 8
    x = 8
    y = 37
    )

  45. i'm asian

    ok guess my name says it all.. correct answer is

    y is dad, x is son

    1.

    y+5 = 4(x-1) —- 1
    y+5 = 3(x+6) —- 2

    Solving it gives

    dad = 79, son = 22

    2

    y+3=4(x+2) —– 1
    y+3=5x

    Solving it gives
    dad = 37 , son = 8

    not gonna write how it’s solved i’m pretty sure u can do that..

  46. i'm asian

    ok guess my name says it all.. correct answer is

    y is dad, x is son

    1.

    y+5 = 4(x-1) —- 1
    y+5 = 3(x+6) —- 2

    Solving it gives

    dad = 79, son = 22

    2

    y+3=4(x+2) —– 1
    y+3=5x —— 2

    Solving it gives
    dad = 37 , son = 8

    not gonna write how it’s solved i’m pretty sure u can do that..

  47. bella

    i’m a kid :) ))))))))))))
    im 9 yrs old

    from united states university

    ok guess my name says it all.. correct answer is
    y is dad, x is son
    1.
    y+5 = 4(x-1) —- 1
    y+5 = 3(x+6) —- 2
    Solving it gives
    dad = 79, son = 22
    2
    y+3=4(x+2) —– 1
    y+3=5x
    Solving it gives
    dad = 37 , son = 8
    not gonna write how i will ans this :) )

  48. bella

    is it correct? :D

  49. bella

    :P k k k alright yeah
    dora the explorer
    hhehehehehehehehhhe

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